Electromagnetic signaling device



D. D. MILLER ELECTROMAGNETIC SIGNALING DEVICE Oct. 11, 1932.

Filed Jan. 16, 1929 (INVENTOR [7. 0. M/LLER ATTORNEY DANIEL n. MILLER, OF NEW YORK, N. in, ASSIG-NOR To BELL TE nPn'onE LA'BoI'eA Patented Oct. 11, 1932 TORIES, INCORPORATED, 015 NEW YORK, N. Y., 'A. CORPORATION OF YORK n'nno rnomnenn'rro SIGNALING innvron Application filed. January 16, 1929. Serial No. 332,824.

This invention relates to electromagnetic signaling device and 1n particular to rlngers for telephones.

An object of this invention is to efliciently transform electrical signaling energy into sound energy through the use of gongs or other vibratory devlces.

Another object of this invention is the pro-i duction of an electromagnetic ringer with a minimum number of parts, which has high sensitiveness and which will hold its adjustment over a long period of time.

According to onefeature of this invention a single operating coil is employed.

Another feature resides in the employment of a balanced magnetic circuit having an armature of the cantilever beam type fixed at one end and arranged withinthe operating coil, the stiffness of the armature being such as to offset the pull exerted by the magnetic flux. The permanent magnet is on opposite sides of the operating coil with its pole pieces on opposite sides of the free end of the armature. An extension from the armature carries a bell clapper which is placed between a pair of signal gongs in the well known manner.

l/Vith no current flowing through the winding of the energizing coil, the flux from the I permanent magnet exerts a pull on the armature in either direction, the cantilever type armature being in a balanced neutral position between the pole pieces of the magnet. If desired, the stiffness of the armature may be islightly greater than is necessary to offset the pull exerted by the permanent magnet and therefore a very small flux generated in the armature by a current flowing through the energizing winding of the operating coil 3 is sufficient to disturb the balance between the armature and the pole pieces causing movement of the armature and sounding of the gongs. V Due to the fact that such a small amount of i electrical energy is required to cause the movement of the armature, a highly efficient and sensitive ringer is obtained through the jheretofore but they have been inefiicient modifications of the commonlyuseditwocoil ringer. Others have had the armature rigidly attached to the operating coils with.

the, operating coils pivoted so asto, move with the armature. Such ringers are capable of handling a large amount of power but are ATENT oFFrcIa F y obviously very inefficient at low energy-levels.

Referring now to the drawing, Fig. lis a front, view of a singlecoil ringer with-a portion of the operating coil and'spool. shown in section. J V c g Fig 2 isa side view of the ringer with a, portion of the magnet and frame broken away to show the connection of the clapper to the armature.

The relay frame 4: "of magnetic ironis equipped with mounting lugs 55 provided with mounting holes 66 whereby the device may beattached to a suitable base. 17 :This frame has extensions 77 which serve as pole pieces of. the device. The armature 8 is rigidly clamped between the pole pieces 77 by the nuts 9 threaded on. screws 10, butis sepa rated fromthe pole-pieces by the non-magi netic shims 1111. By the use of these shims high reluctance gaps "are provided between, the pole pieces and the armature, thereby providing magnetic poles andfixed air gaps where the armature. is clamped in position. As a result of thisconstruction, the effects of residual magnetism are largely overcome and the desired balanced magnetic circuit is retained with its advantages of high sensi tivity.

The operating coil 12 is provided with spoolheads 13-13 of insulating material.

These spoolheads are provided with eXtensions 1t1t which extend into and fit'tightly within openings 1515 in the side walls of theframe 4 thus supporting the operating coil 12 within the frame. Thecore oftheop-Q erating coil 12 is hollow and is so dimensioned as to allow ample clearance for the operation of the armature 8 whichpasses through it.

' it screw 18 passes through opening 19in the side walls of the frame 4, below the oper ating coil 1 and on this screw is threaded the nut 20.; the screw 18 and the nut20serving to against the 'spoolheads 13-43. y

hold thesidewwalls of the frame. 4; tightly V V gongs 2828.

The U-shaped permanent magnet 21 serves to polarize the ringer. The magnet 21 passes around the operating coil 12 and is clamped to the frame 1 between the clamping lugs 2222 and the mounting lugs 5'5. The frame 4, below the operating coil 12 has a threaded hole in .each of its walls which are adapted to engage the threadsof the adjusting screws 2 l 24 which are of magnetic materialand which act as extensions to the pole pieces. The lock nuts 25 -25, when the adjusting screws 242t are once adjusted, serve to lock these adjusting screws in position.

The bell clapper rod 26 has its lower end forced into the hole 27 in the free end of the armature 8 to make what is known as a drive bell clapper 29. The support for these o: gongs is not shown.

The proportions and material of the arma 'ture 8 are so chosen that its stiffness to bend- =magnet 21 at the pole pieces 24- 2. A very small flux generated in the armature 8 by a current flowing through theoperating coil 12 issufiicie'nt to disturb'the balance between the. armature 8 and the pole pieces 2424 causing movement of the armature 8 and bell clapper 29 and resultant sounding of the That is claimed is:

1. An electromagnetic device comprising an operating coil, an armature, a U -shaped permanent magnet and atwo element support provided with integral clamping means for securing said permanent magnetln contiguous relation with each element of said support, with apertures in each element thereof which accommodate the spoolhea'ds of-said coil and maintain said coil in fixed relation with said permanentmagnet and with flanges between which said armature is supported as a cantilever beam within said coil, said support constituting a magnetic pathfor the flux set up by said device and carrying adjustable pole pieces in operative association with the free end of said armature. r S r 2. An electromagnetic device comprising an operating coil, an armature, a U-shaped permanent magnet, a two element support provided with clamping means for securing said permanent magnet in contiguous relatlon with each element of said support, with apertures in each element thereof which accom modate the spoolheads of said coil and maintain said coil in fixed relation with said permanent magnet, and with flanges between which said armature is supported as a cantilever beam within said coil, said support constituting a part'of the'magnetic 'c'ircuit of" said-device and carrying adjustablepolepieces in operative association with the free 'lll) 

